• The KIPS Transactions:PartD
• /
• v.13D no.6 s.109
• /
• pp.797-806
• /
• 2006

In the data warehouse environment, materialized views are typically used to support efficient query processing. Materialized views need to be updated when source data change. Since the update of the views need impose a significant overhead, it is essential to update the views efficiently. Though various view maintenance strategies have been discussed in the past, the efficient maintenance of SPJ materialized views has not been sufficiently investigated. In this paper, we propose an efficient incremental view maintenance method for SPJ materialized views that minimizes the total accesses to data sources. The proposed method finds an optimal view maintenance strategy using a dynamic programming algorithm. We also present various experimental results that shows the efficiency of our proposed method.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2012.07a
• /
• pp.164-166
• /
• 2012

In this paper, we proposed a method for extracting predominant melody of polyphonic music based on harmonic structure. Harmonic structure is an important feature parameter of monophonic signal that has spectral peaks at the integer multiples of its fundamental frequency. We extract all fundamental frequency candidates contained in the polyphonic signal by verifying the required condition of harmonic structure. Then, we combine those harmonic peaks corresponding to each extracted fundamental frequency and assign a rank to each after calculating its harmonic average energy. We run pitch tracking based on the rank of extracted fundamental frequency and continuity of fundamental frequency, and determine the predominant melody. For the query by singing/humming (QbSH) task, we proposed Dynamic Time Warping (DTW) based matching engine. Our system reduces false alarm by combining the distances of multiple DTW processes. To improve the performance, we introduced the asymmetric sense, pitch level compensation, and distance intransitiveness to DTW algorithm.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.18 no.4
• /
• pp.415-421
• /
• 2000

The purpose of this study is to develop the AM/FM system for a university using internet GIS. Because the developed system has an additional Java Applet functions, web user can execute dynamic data processing including static HTML GUI. The developed internet AM/FM system could be used for effective management work exact search and inquiry of both graphic information and attribute information rapidly. Also, it has the functions of mapping, attribute and spatial information searching, spatial query processing, etc.. Besides, this system could be used for realtime facility in any place or office using internet.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.2 no.2
• /
• pp.83-91
• /
• 2007

The purpose of this paper is developing a PML server which is capable of saving and managing effectively the information of vehicles using RFID technology in the logistical and distributive environment. The PML server logs and manages the real-time static and dynamic information about the vehicles in EPC code format which is represented by XML schema and transmitted by the RFID reader to the server. It receives information from SAVANT the RFID middleware and transmits the data to the traffic information management application The main system we developed consists of the EPC data registry, query processor, data converter, vehicle product and instance data storage, system management tool and application API parts.

• Journal of KIISE:Databases
• /
• v.29 no.5
• /
• pp.404-415
• /
• 2002

In this paper, we address the issue of ensuring consistency of multiple data items requested in a certain order by read-only transactions in a wireless data broadcast environment. To handle the inherent property in a data broadcast environment that data can only be accessed strictly sequential by users, we explore a predeclaration-based query optimization and devise two practical transaction processing methods in the context of local caching. We also evaluate the performance of the proposed methods by an analytical study Evaluation results show that the predeclaration technique we introduce reduces response time significantly and adapts to dynamic changes in workload.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2010.05a
• /
• pp.756-758
• /
• 2010

Fixed frame size is used in the RFID system with the frame-based slot ALOHA algorithm. Therefore, it is anticipated that the tag identification performances will highly depend on the number of tags within the reader's identification range and the frame size. In this paper, we propose a tag number estimation scheme and analyze the performance with the computer simulations. The proposed scheme is based on the status of slots that the tags respond during a query round as well as the probabilistic calculations.

• Journal of Information Management
• /
• v.42 no.1
• /
• pp.63-83
• /
• 2011

Mashup service provides results by query in real time and responds to users' request in dynamic. In terms of size, each of NIKH(National Institute of Korean History)'s internal Information Systems is equal to individual library system. As adapting mashup for information convergence with external resources, it was accepted for internal integrated search in the same context. This study designated NIKH OpenAPI and proposed metadata format for internal integrated search of historical contents.

• Journal of Korea Spatial Information System Society
• /
• v.12 no.1
• /
• pp.18-27
• /
• 2010

In u-GIS environment, GeoSensor environment requires that dynamic data captured from various sensors and static information in terms of features in 2D or 3D are fused together. GeoSensors, the core of this environment, are distributed over a wide area sporadically, and are collected in any size constantly. As a result, storage space could be exceeded because of restricted memory in DSMS. To solve this kind of problems, a lot of related studies are being researched actively. There are typically 3 different methods - Random Load Shedding, Semantic Load Shedding, and Sampling. Random Load Shedding chooses and deletes data in random. Semantic Load Shedding prioritizes data, then deletes it first which has lower priority. Sampling uses statistical operation, computes sampling rate, and sheds load. However, they are not high accuracy because traditional ones do not consider spatial characteristics. In this paper 'Pre-Filtering based Post Load Shedding' are suggested to improve the accuracy of spatial query and to restrict load shedding in DSMS. This method, at first, limits unnecessarily increased loads in stream queue with 'Pre-Filtering'. And then, it processes 'Post-Load Shedding', considering data and spatial status to guarantee the accuracy of result. The suggested method effectively reduces the number of the performance of load shedding, and improves the accuracy of spatial query.

• Journal of Korea Multimedia Society
• /
• v.10 no.2
• /
• pp.269-277
• /
• 2007

Network clustering has been proposed to provide that sensor nodes minimize energy and maximize a network lifetime by configuring clusters, Although dynamic clustering brings extra overhead like as head changing, head advertisement, it may diminish the gain in energy consumption to report attribute tasks by using cluster heads. Therefore, this paper proposes a new routing algorithm which configures cluster to reduce the number of messages when establishing paths and reports to the sink by way of cluster heads when responding sens ing tasks. All sensor nodes only broadcast bitmap once and maintain a bitmap table expressed by bits, allowing them to reduce node energy and to prolong the network lifetime. After broadcasting, each node only updates the bitmap without propagation when the adjacent nodes broad cast same query messages, This mechanism makes nodes to have abundant paths. By modifying the query which requests sensing tasks, the size of cluster is designed dynamically, We try to divide cluster by considering the number of nodes. Then, all nodes in a certain cluster must report to the sub- sink node, The proposed routing protocol finds easily an appropriate path to report tasks and reduces the number of required messages for the routing establishment, which sensor nodes minimize energy and maximize a network lifetime.

• Journal of Internet Computing and Services
• /
• v.10 no.3
• /
• pp.131-140
• /
• 2009

Recently, the information visualization research community has given significant attention to graph visualization, especially visualization of social networks. However, visualization of information flows in a very large social network has not been studied in depth. However, information flows are tightly related to the structure of social networks and it shows dynamic behavior of interactions between members of social networks. Thus, we can get much useful information about social networks from information flows. In this paper, we present our research result that enables users to navigate a very large social network in Google Maps' method and to take a look at information flows on the network. To this end, we devise three techniques; (i) mapping a very large social network to a 2-dimensional graph layout, (ii) exploring the graph to all directions with zooming it in/out, and (iii) building an efficient query processing framework. With these methods, we can visualize very large social networks and information flows in a limited display area with a limited computing resources.